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The CHP is investigating a group of about 300 motorcyclists who shut down the 10 freeway in West Covina, Calif., for a marriage proposal Sunday afternoon. Charges could range from misdemeanors to felonies for impeding traffic. Angie Crouch reports from West Covina for the NBC4 News at 5 p.m. on Jan. 29, 2013. (Published Wednesday, Jan 30, 2013)

Updated at 7:36 AM PDT on Wednesday, Jan 30, 2013

After several hundred motorcyclists shut down the 10 Freeway so one biker could propose to his girlfriend on the pavement, the California Highway Patrol says criminal charges could be filed.

A YouTube video of the dramatic interstate proposal, posted below, drew attention to the event, which happened Sunday under a freeway overpass in West Covina, about 20 miles east of Los Angeles.

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In the video, many dozens of motorcyclists occupied all eastbound lanes of the freeway, with the pack headed toward the overpass where family members were gathered, looking down.

After emitting a cloud of pink smoke from his motorcycle, a biker got down on one knee before his girlfriend, who was still wearing her red helmet. Several other bikers did wheelies off to the side, with between 300 to 400 bikers behind them.

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With smoke swirling, the other bikers gathered around the couple, who got a few congratulatory hugs. The new fiancée looked shocked.

Then they got back on their bikes and cruised forward, some bikers pumping their fists in the air. Regular vehicle traffic, backed up, started moving again as most of the bikers exited the freeway at Barranca Street.

"Hector 'Tank' Martinez proposed to Paige Hernandez in front of his family and friends," the YouTube caption reads. "Big ups to the 710 Bikerz and everyone else who took part in this event."

But the agency is investigating and said about 20 motorcyclists were cited for traffic violations that occurred on surface streets after the proposal. Potential charges could range from various misdemeanors to felonies for impeding traffic, according to CHP Officer Jose Barrios.

"It’s a public safety issue as well," Barrios said. "Reckless driving, stopping when it’s not an emergency stop -- just a few of the violations they were committing at the time."

Katy Lacy, who works at nearby coffee shop, said the pack of motorcyclists made such a commotion that she had to stop taking orders for about 10 minutes.

"It was very loud," Lacy said. "A lot of smoke in the air."

Nonetheless, she said she found the grand gesture quite romantic, even if it irritated hundreds of motorists.

It's not the first a stunt has shut down a Southern California freeway. In October 2010, an Orange County band forced the the 101 Freeway to close in Hollywood and got out of a truck to play a song about the roadway.